Some 300,000 rounds of ammunition are said to have been fired by British troops defending places like Sangeen and Musa Qaleh.

Nato's military commander, General James Jones, said the alliance was taken aback by the intensity of the Taleban campaign.

Commanders have been surprised, too, by the Taleban tactics. They expected classic guerrilla hit-and-run attacks but, instead, the Taleban have been carrying out wave after wave of frontal assaults on the British bases.

In Sangeen, for instance, a handful of British paratroops have found themselves facing similar, or greater, numbers of Taleban fighters. The battle is sometimes grenade against grenade, British SA-80 automatic weapons against Taleban Kalashnikovs.

The lightly-armed British soldiers often have to call for air support from American A-10 Tankbusters or British Apache helicopters.

The soldiers can be cut off - for days or even weeks at a time - in these isolated forward positions. Re-supply is difficult, and sometimes only possible by helicopters, of which there are not enough.

Commanders describe the Taleban behaviour as reckless, throwing people forward into exposed positions and losing many of them. That's why Nato thinks it has killed 1,000 insurgents over the course of the summer.

Military sources say they believe the campaign has turned a corner, with the Taleban not beaten but certainly broken up into smaller groups.

The nature of the fight will therefore change, say these military sources. There will be more emphasis put on mobility to chase and capture or kill these smaller bands of Taleban. British forces will be mounting long-range patrols from the bigger, rear bases in Helmand province.

The risk for the coalition is that a change of tactics could look like a propaganda victory for the Taleban. And no military source I've spoken to pretends the conflict in Afghanistan will be anything other than difficult and bloody.

For the most part, British paratroops are not engaged in peacekeeping or reconstruction but in a counter-insurgency warfare.

What is the exit strategy? Is victory achievable?

Victory will depend, in that cliched phrase, on winning the "hearts and minds" of ordinary Afghan peasants.

But those are the same Afghan peasants to whom the army is saying "don't grow opium anymore, even though it's your main source of income".